This invention relates to a wheel for a motor vehicle having a wheel disk portion which comprises several radial hollow spokes, is produced in a die tool and is connected with a rim well portion, a cast wheel disk portion being connected with a rim well comprising a deformed part via friction welding in the area of a ring flange. The wheel disk, on an interior side, has at least one flat welding surface which extends around as an annulus and corresponds with another opposite flat welding surface of the rim well.
In the case of wheels for motor vehicles made of cast metal, because of the fact that the wheel disk and the rim well are in one piece, a complicated sand core is required in the diecasting tool in order to be able to produce a wheel that is light in weight by means of a simple casting method. For those wheel rims with a direct connection to the wheel flange, accumulations of material are required in the area of the connection of the spokes to the rim well, and the casting of arbitrarily wide rim formats is limited. Also, the arrangement of the sand core parts between the cores of the diecasting tool for the formation of hollow spokes with constant wall thicknesses is possible only inadequately because of an insufficiently secured bearing of the core.
An object of the invention is to provide a wheel and a process for manufacturing the rim which in a simple manner can be manufactured in various dimensions and with a low weight.
It is another object of the invention to provide a wheel with a disk rim having hollow ribs that, while having a relatively small wall thickness, are constructed with high stability.
This and other objects are achieved by the present invention which provides a process for the manufacturing in a diecasting tool of an aluminum wheel with a cast wheel rim disk comprising a plurality of hollow spokes, the wheel disk being connected with a rim well consisting of a formed part. The wheel disk has an interior side with at least one plane welding surface which extends around the rim in a ring-shaped area, and the rim well has a corresponding plane welding surface. The process comprises arranging the plane welding surface of the wheel disk opposite the plane welding surface of the rim well, and connecting the wheel disk with the rim well by friction welding in an area of a rim flange of the aluminum rim.
The objects are also achieved by a wheel constructed according to the present invention which provides an aluminum wheel rim with a cast wheel wheel disk comprising a plurality of hollow spokes, the wheel rim disk being connected with a wheel rim well consisting of a formed part. The wheel rim disk has an interior side with at least one plane welding surface which extends around the wheel rim in a ring-shaped area, and the rim well has a corresponding plane welding surface, the plane welding surface of the wheel disk opposing the plane welding surface of the rim well. The wheel disk is connected with the rim well by friction welding in an area of a rim flange of the aluminum rim.
Some principal advantages achieved by means of the invention are that two separate constructional elements of the wheel can be connected with one another and therefore the casting operation for the wheel rim disk becomes possible by means of a sand core in the bottom core of the diecasting tool which is easy to support, and which, in addition must also be supported in a precise manner. The rim well can therefore be manufactured according to a different manufacturing technique, for example, by means of extruding or by hot-forming a blank so that a complicated diecasting tool is not required. Also, by using different manufacturing methods for the rim well and the rim disk, arbitrarily wide rim formats can be produced, and the rim well may then also consist of a different material than the wheel rim disk, which results in important advantages with respect to weight.
Because of the separation of the wheel rim disk from the rim well during the manufacturing of the two elements, a better castability of the wheel disk is achieved. In addition, a good supporting of the sand core becomes possible for the formation of hollow spokes with small and definitely uniformly thick wall thicknesses.
The two elements of the wheel, such as the wheel rim disk and the rim disk well are undetachably connected with one another by friction welding. For this purpose, the wheel rim disk has, on the interior side in the area of the rim space, two walls with face-side welding surfaces which are opposite corresponding welding surfaces on the rim well. Between the walls of both elements, a closed ring duct is formed which is connected with the space of the hollow spoke. As a result, the rim well forms a tight closure with respect to the fitted tire and a separate sealing of a space of the hollow spoke leading into the rim well.
According to the conditions, the welding surfaces on the faces of the walls of the two elements may be arranged either in a common plane or in different planes. This depends on the construction and is a function of the position of the hump on the rim well.
The supporting of the sand cores for the manufacturing of the rim, particularly in the area of the hollow spokes, is possible in different manners which takes place as a function of the construction of the hollow spokes. For example, the supporting of the sand cores takes place differently depending on whether these hollow spokes extend continuously directly to the hub; end at a distance from the hub; end in the fastening bores of the rims; or end in front of the fastening bores. In each of these cases, a sand core in the hollow spokes can be used for the forming of the hollow spokes which, because of its precise support, causes a uniformly relatively thin wall thickness of from 3.5 to 4 mm.
The aforementioned objects are also achieved by an embodiment of the present invention which provides a wheel with a cast wheel disk comprising a plurality of hollow spokes, the wheel disk being connected with a rim well that is a formed part. The wheel disk has an interior side with at least one plane welding surface which extends around the wheel in a ring-shaped area, and the rim well has a corresponding plane welding surface. The plane welding surface of the wheel disk is arranged opposite the plane welding surface of the rim well, and the wheel disk is connected with the rim well by friction welding in an area of a wheel flange of the aluminum rim. A hollow space is provided within at least one of the hollow spokes and has at least two opposite walls. A reinforcing rib is arranged in the hollow spoke to extend radially from a wheel center axis toward the outside of the wheel disk rim, wherein the reinforcing rib connects the two opposite walls with one another.
Some of the advantages achieved by the present invention are that the hollow ribs, while they have a relatively thin wall thickness, are reinforced by a rib situated in the interior. This reinforcing rib extends radially from the wheel hub approximately to the rim well and connects an exterior wall with an interior wall of the hollow space in the reinforcing rib. In the perpendicular direction, it is aligned in a vertical plane extending through the wheel spin axis and divides the rectangular hollow space into two chambers of approximately the same size. This hollow space has its largest width between two openings of the rim.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.